Lamp basing method



Jan. 31, 1956 c. E. BECHARD ETAL LAMP BASING METHOD 2 Sheets-Sheet 1 Filed Oct. 6, 1952 Inventors: Conrad E. Bechard,

n o v/ m% a m m 0 F t e t HM! E w e m h m T w W Jan. 31, 1956 c. E. BECHARD ETAL ,8

LAMP BASING METHOD Filed Oct. 6, 1952 2 Sheets-Sheet 2 lnventohs: Conhaol E. BGChQFd, H rman E. Hermanson, byM

Their At or-ney United States Patent F LAMP BASING METHOD Conrad E. Bechard, Mayfield Heights, and Herman E. Hermanson, East Cleveland, Ohio, assignors to General Electric Company, a corporation of New York Application October 6, 1952, Serial No. 313,276

3 Claims. (Cl. 1531) This invention relates generally to electric lamps and similar devices comprising avitreous bulb having outwardly projecting lead wires and a base including a shell serving as a terminal for one of the wires. The invention is more particularly concernedwith an improved method of making the electrical connection between the side lead-in wire of thelampand the shell or cylindrical portion of its base.

The present application is a continuation-in-part of my copending application Serial No. 263,457, filed December 26, 1951, now abandoned. It presents certain improvements in the method disclosed in the parent application for basing electric lamps and connecting the side lead-in wire to the shell of the base.

The common sizes of incandescent lamps for household use and many flash lamps are providedwith a base comprising a cylindrical metal shell and an insulated end contact or eyelet. The shell is threaded in order to allow screwing into a socket and serves as one terminal for the filament circuit whereas the end contact serves as the other. The base is mounted on the neck of the lamp, that is, on the constricted and generally cylindrical extension of the main spherical portion of the bulb, and is usually cemented in place.

The common practice until quite recently has been to use brass as the metal of the shell and end contact of the base, and to make the electrical connections of the lead-in wires to them by soldering. More recently, it has become more than ever desirable to replace brass by some other metal such as aluminum, for the bases of electric lamps, particularly for the shell which contains by far the greater portion of the metal comprised in the base. However, aluminum is both diflicult and expensive to solder so that a convenient and eifective means for making a solderless connection between the side lead-in wire of an electric lamp and the shell of its base is needed.

An expedient which has been attempted for eliminating the solder connectionhas been to' 'utilize a full blown 2,732,878 Patented Jan. 31, 1956 and the lamp will be defective. The extent to which any particular manufacturing operation reduces the percentage of good lamps in process is generally termed the shrinkage factor. It will be realized that in the commercial production of electric lamps, the shrinkage factor is of prime importance and must be kept within very low limits. Attempts to achieve a mechanical side lead-in wire connection solely through a full blown seal construction have generally resulted in a shrinkage factor too high to be economically feasible.

An object of the invention is to provide new and improved methods for basing electric lamps and connecting the .side lead-in wire to the shell of the base with a low shrinkage factor in commercial production.

In accordance with the invention, the lamp comprises a bulb having a full blown seal, that is, a seal whereof the shoulder conforms closely to the inner diameter of the skirt or edge of the base. The side lead-in wire extends out from the interior of the bulb through the stem press and is drawn out along the outside of the seal and wedge between the seal shoulder and the shell near its lower edge or rim. In order to allow for manufacturing tolerseal and a close fitting base" whereby to wedge the side lead-in wire between the seal shoulder and the skirt of the shell when the base is pressed on the neck of the bulb. The seal in question here is the vitreous portion in the region where the flare tubeis fused to the neck during the sealing operation. By forcing air under pressure into the bulb while the seal is still plastic from the heat of the sealing-in fires, -,it is possible to blow out or expand the seal shoulder to the size of a mold positioned around it. Although this expedient appears in theory quite simple, it is in fact difiicultto utilize effectively in the commercial production of electric lamps. The reason for this is that both the bulb and the shells being mass produced, they are unavoidably subject to considerable dimensional variation. If the seal is too large for the shell of the base, the base will not seat squarely, or the bulb neck will crack when the base is forced down upon it. On the other hand if the .seal is too small and the shell of the base fits loosely, the result will be an intermittent contact to the side lead-in wire cylindrical shell of the base.

ances, the dimensions of the seal and of the shellare permitted to vary in the direction of a loose fit rather than in the opposite direction. Thus the possibility of cracking the seal by forcing an excessively tight fitting base on it is avoided. In order thereafter toinsure a reliable electrical connection between the lead wire and the shell, the shell is indented inwardly along a line transverse to the direction in which the lead-in wire lies, resulting in a raised line or ridge on its inside surface, which ridge traverses the lead-in wire. The lead-in wire becomes embedded in the ridge at the point of crossover, and a firm electrical contact is thereby assured. In a mechanism operating in conjunction with a prior art lamp finishing machine for basing electric lamps in accordance with our invention, there is provided a sharp pointed tool which is resiliently mounted in the path of movement of the base. This tool engages the base and forms the indentation as the lamp is carried past it.

For further objects and advantages and for a better understanding of the invention, attention is now directed to the following description and to the accompanying drawings. The features of the invention believed to be novel will be more particularly pointedout in the appended claims.

In the drawings:

Fig. l is a side sectional view through the neck portion of an incandescent lamp embodying the invention and illustrating the inward indentation of the base transversely to the side lead-in Wire. Fig. 2 is a side view of the lamp seen at right angles with respect to the view of Figl l. Y

Fig. 3 shows in plan the placement of an indenting mechanism operating in conjunction with a prior art type of lamp finishing machine for manufacturing electric lamps in accordance with the invention.

Fig. 4 is a side elevation, partly in section, of an indenting mechanism. I

Fig. 5 is a plan view of an improved form of indenting mechanism with a fragment'of a prior art typeof lamp finishing machine. Y i

The invention will be described with reference to an ordinary screw base of the typegenerally used for household incandescent lamps. It will be understood however that the invention is equally applicable to different sizes of lamps, and also to different types of bases wherein the same general problem of a side contact is encountered. For instance the invention may be used with bayonet type bases wherein it is desired to effect aconnection between the 'side lead in, wire and 'the straight-walled Referring to Figs. 1 and 2 which illustrate the fastening of the base in the case of an ordinary incandescent lamp, the base 1 is mounted on the constricted upper neck portion 2 o'f an evacuated glass bulb of which a fragment is shown at- 3. The bulb may be of conventional construction and containing a filament (shown in Fig. 4) mounted on the endsof the lead-in wires 4 and 5 whichare sealed into the insideof the bulb through the glass press .6. Y

The base comprises a threaded metal shell 7, an insulating body or web 8, and an end contact 9 fastened tol t-he upper surface ofthe web. The base is permanently fastened to the neck of the bulb by means of a cement indicated at 10. Previous to the assembly of the base to the bulb, a quantity of cement is disposed within the inside of the base as anannular ring which is preferably located a slight distance inwardly from its outer edge in order to insure that the cement will not enter the contact region between the lead wire and the shell. Since the basing cement is an insulator, it would interfere with the contact and might cause a defective electrical connection were it allowed to enter the contact region. The connection of the top lead-in wire 4 of the bulb to the end contact may be made in the usual manner by soldering as indicated at 11.

The invention is more particularly concerned with the means for and manner of effecting the connection be- 4 scribed in U. S. Patent 1,708,756 Fagan, comprising a turret or reel, of which a fragment is shown at 22, having mounted on its periphery a plurality of lamp holding fixtures or heads 23. It will be understood that the reel is provided with suitable means for rotating it in a counter-clockwise direction as-indicated by the curved arrow 24. Such means may comprise a supporting shaft and an intermittent drive mechanism coupled thereto of the usual type employed in the art and adapted to advance the heads from one position to the next for each indexing movement.

Each larnp holding head comprises a top plate 25 having an opening or recess 26 for receiving the end tween the side lead-in wire 5 and the shell '7 of the base.

As illustrated in Fig. 1, the seal of the bulb comprises an end-portion 12 which is generally annular and perpendicular to the axis of the bulb. Immediately adjacent the'annular portion 12 is a generally cylindrical portion 13 of a diameter slightly less than the root diameter of the threads of the shell. This permits the disposition of the cement at it) for making a permanent fastening. The straight cylindrical portion '13 merges into the main body 2 of the neckthrough a shoulder comprising an expanded portion 14 and a conical or flaring portion 15.

A connection between the side lead-in wire 5 and the shell 7 of the base occurs at 17 between the skirt of the shell and'the expanded portion 14. The outer diameter of the portion 14and the inner diameter of the shell are proportioned to give a tight fit in the region 17. However since dimensional variations unavoidably occur in mass production, these parts are allowed to vary in the direction of providing a looser fit than the optimum. Under no circumstances are they allowed to vary in the direction of providinga'tighter fit because such would result in failure of the base to seat squarely on the bulb, or in cracking the neck of the bulb when the base is forced down upon it. Accordingly, the parts are proportioned to obtain a fit which is as tight as possible, due regard being had to the required manufacturing tolerances, and, in accordance with the invention, a firm and reliable contact connection is achieved by indenting the skirtof the base inwardly along a line transverse to the side lead-in wire, as shown at 18 in Fig. 2. The incontact 9 of the lamp, and a. cup 27 mounted on a spindle 28 which is biased upwardly by means of a spring 29. The cup 2'7 thus urges the lamp upward and forces the base to seat firmly on the neck of the bulb. In addition there is provided a pair of spring-loaded jaws 30 and 31 which are pivoted together to encompass the base on opposite sides and which assist in straightening it on the neck of the bulb.

In the manufacturing process,.the bulb 3 with its base I mounted upon it is inserted into a head of the turret at a loading station by an operator. Before arriving at the base indenting position, the base-is heated in order to set the basing cement, the top lead-in wire may be cut off and soldered to the end contact, and the side leadin wire is cut ofi short at the edge of the base.

i The indenting apparatus shown in Figs. 3 and 4 corn prises a bracket 33 which is fastened to a pedestal 34 attached to the frame or bed plate of the machine. The bracket supports a plunger 35'which is arranged to slide within a channel '36. Plunger 35 is urged forward by the edge of the base as the lampis moving past it and in ward indenting may be done by swinging a pointed tool such as indicated at 19 in Fig. 1, along the circumferw ence of the shell near its edge and transversely to the direction in which the lead-in wirelies. Thus the ridge on the inside surface of the shell resulting from the indentation is sure to pass over the lead-in wire. The lead-in wire becomes slightly embedded in the ridge at the crossover point 20 and a reliable electrical connection results. By reason of the fact that the indentation is narrow, it may be achieved with the application of a comparatively small force on a sharp pointed tool, and the neck of the bulb is able to withstand that force when the lamp assembly is suitably supported.

Referring to Figs. 3 and 4, there is shown an indenting mechanism adapted to operate in conjunction with the prior art type of finishing machine for the manufacture of incandescent lamps in accordance with the invention. The finishing machine, which may be similar to'that dethe process causes an indentation or furrow to be made as desired.

In Fig. 5, there isshown an "improved form of indenting apparatus which has been found superior to that of Figs. 3 and 4 in avoiding breakage of bulbs during the indenting operation. The mechanism comprises a sharp edged roller 51 which is rotatably mounted at 52 on the end of an arm '53. The arm is pivotally mounted at 54 upon a bar 55 which is fastened by means of a bracket 56 to a pedestal member 57 attached to the frame or bedplate of the lamp finishing machine. The arm 53 is resiliently pivoted'into the'path of travel of the bulb holders 23 by means of a pull rod. 58' whereof the shank passes through an oversized ,hole at 59 in a bracket '61. fastened to the supporting bar 55. The portion of the pull rod 58 projecting to the rear of the bracket 61 is provided with a spring 6 2-which is compressed between the bracket and an end nut 63. 4 A stop ring 64 on the opposite side of bracket 61 from spring 62 limits the movement of the pull rod topreventthe'roller 51 fromswinging too far forward into the path of travel offthebulbhol'ders.

The minimizing nfdamp breakage achieved by the mechanism of Fig. 5 .is due tothe different manner of mounting the 'roller 51 whereby it pivots about an arc whose center at 54 is to the rear of the point of engagement of the roller with the lamp, the term rear being relative to the path of travel of the bulb holders as indicated by the arrow .24. As a result, any tendency which might be present for the roller 51 tojam in place is eliminated since it is merely pivoted outof .the way by the base of. the 'lampBiin the bulb holder as itapproaches station B. This permits the pressure which the roller exerts on ant)- the base to be closely regulated by adjusting the compression of the spring 62 through the lock nut 63 on the end of'pull rod 58.

Fig. also illustrates an improved method for basing electric lamps. It has been found that when the indenting operation is performed after the basing cement (shown at in Fig. 1) has been heat-cured, occasionally a lamp is produced which has an intermittent or high resistance side contact. 'This was due to the entry of basing cement into the region 17, which cement having become hardened by heat-curing, the inward indentation of the edge of the shell fails to force it out completely so as to give a good contact. In accordance with a new feature of the inven tion, the difiiculty may be obviated by performing the indenting operation before the heat-curing of the cement. Thus referring to Fig. 5, the bulb 3 with the cement filled base mounted on it is inserted into a holder of the finishing machine at station A; Next, the indenting operation is performed at station E at a time when the basing cement is plastic and easily forced aside in the region of the indentation. Thereafter, the base is subjected to heat treatment as at station C Where flames 66 are directed upon the lamp base by the gas burners 67. Finally the side lead wire may be sheared off and the top lead wire soldered to the'end contact and the finishing operations completed in. the usual fashion.

Where the side lead wire is sheared oil? by pulling it upward against the edge of the base shell, it occasionally happens that a slight burr or bump is produced in the edge of the base shell. This may cause a poor connection and, in any case, such a burr being unsightly, it is desirable to remove it. This may readily be effected by using again a mechanism similar to that of Fig. 5 but wherein a roller is used which has a blunt or flat edge. The height of the roller relative to the base is adjusted so that it passes over the burr and presses it in.

The apparatus which have been described illustrate preferred means for manufacturing electric lamps in ac cordance with the invention. It will be understood how ever that other apparatus may be utilized for carrying out the methods and achieving the desired structure. It will also be understood that whereas a specific lamp embodying the invention has been shown and described, the invention is not to be limited thereto and its scope is to be determined by the following claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. The method of basing an electric lamp including a vitreous bulb having a neck portion and a lead-in wire emerging therefrom with a base including a metal shell adapted to fit tightly on said neck portion which comprises the steps of seating the base on the neck portion with the lead-in wire drawn out between them and indenting the shell inwardly along a line crossing over the wire.

2. The method of achieving a firm contact connection between the side lead-in wire and the shell of the base in an electric lamp where the lead-in wire is wedged between the seal shoulder and the inside surface of the shell which comprises indenting the shell inwardly along a line crossing over the wire to cause the wire to become embedded in the ridge produced thereby on the inside of the shell.

3. The method of basing an electric lamp including a vitreous bulb having a neck portion and a lead wire emerging therefrom with a base including a metal shell adapted to fit tightly on said neck portion and having cement disposed within it subject to heat hardening, which comprises the steps of seating the base on the neck portion with the lead-in wire drawn out between the seal shoulder of the neck of the bulb and the inside surface of the base shell, indenting the shell inwardly along a line crossing over the wire to cause the wire to become embedded in the ridge produced thereby on the inside surface of the shell, and thereafter heating the base to harden and set the cement.

References Cited in the file of this patent UNITED STATES PATENTS 264,654 Edison Sept. 19, 1882 1,338,886 Van Doorn May 4, 1920 1,559,415 Fuller Oct. 27, 1925 1,578,649 Ely Mar. 30, 1926 1,603,921 Peth Oct. 15, 1926 1,629,694 Ford May 24, 1927 1,760,693 Gustin May 27, 1930 1,965,231 Gustin July 3, 1934 2,034,653 Flaws Mar. 17, 1936 2,064,364 Thomas Dec. 15, 1936 2,066,317 Blake et a1 Jan. 5, 1937 2,089,707 Price Aug. 10, 1937 2,119,681 McGowan .4 June 7, 1938 2,132,538 McGowan Oct. 11, 1938 2,278,392 Murphy Mar. 31, 1942 2,336,556 Malloy Dec. 14, 1943 2,359,483 Kuebler Oct. 3, 1944 2,509,259 Wittek May 30, 1950 2,519,328 Whitmore et al Aug. 15, 1950 2,551,376 Hroch May 1, 1951 FOREIGN PATENTS 499,682 Great Britain Ian. 27, 1939 

